I'll add my
two cents here, not just to confirm what others above have said (which is all true), but to maybe help those suffering with CFS in
college, or those who don't know if they have it or not. Hope any of this helps, and please /msg me if you want to talk about it.
I'm 24 now, but had CFS starting midway through my freshman year of college and lasting mostly through those 4 years, with the worst coming freshman and sophomore years. It took a term of missing classes due to sleep and collapsing grades to finally go to a doctor. As others have had happen, I was misdiagnosed completely several times.
First I was told nothing was wrong...twice. Then was told that I wasn't sleeping well because I drank soda. OK, so I stopped drinking soda. Then was told I was tired because I was depressed (it never entered the doctor's mind that it was the other way around). And so on. The most important piece of advice I can give is trust your body! You know what your "normal" is and you know when something's wrong. Just because a doctor (or two or three...) tells you "you're fine...just get to bed earlier", don't necessarily believe it.
As far as classes, I never wanted to tell any profs about it, because I didn't want to be treated differently. This was probably a mistake. The one professor I did tell (because she gave pop quizzes during classes, and I had missed the first two, since I was asleep) was understanding and let me write extra essays in place of the quizzes. The thing is, you should tell a prof sooner rather than later, or they'll think you're just making up excuses for bad grades (especially since, as has been stated, doctors don't really confirm CFS).
As far as scheduling, again you know your body. You know your limits. I knew that I was sick and could never wake up for a 9 or 10 AM class, so intentionally scheduled all 11 AM or afternoon classes. I still missed some of those, but not as many as if it was at 9 AM. Also, I knew I couldn't deal with labs, so chose classes that focused more on essays. Adapt your schedule to your illness. It's not ideal, but it doesn't do you any good taking a 4-hour biochem lab, followed by 2 hours of iceskating.
Trust yourself. You'll get through it. I'm from the "everything happens for a reason" train of thought. In my case, I was a biology major, with plans on being a researcher. Due to the illness, I became a communications major. In retrospect, I would have never switched to that if I wasn't sick. Now I'm very happy, while my friends who toil counting fruit flies are miserable. Being sick might have been the best thing to happen to me. I understand myself, physically and emotionally, better than I ever did. Keep the faith.